152 
and taking Fort Assinaboine as a starting-point, 
we obtain the following lines of advance : — 
SCIENCE. 
ie 
[Vor. IIl., No. 5 
The boat, in this case, is connected to 
the balloon by suspension-cords running obliquely; 
on descent. 
Hours FROM Fort ASSINABOINE. 
10. 20. 
40, 50. 
St. Vincent, Minn. 
Huron, Dak. 
North Platte, Neb. 
Cheyenne, Wyo. 
Duluth, Minn. 
St. Paul, Minn. 
Leavenworth, Kan. 
Fort Sill, Tex. 
Santa Fé, New Mex. 
| Marquette, Mich. 
Milwaukee, Wis. 
Chicago, Ill. 
Memphis, Tenn. 
Denison, Tex. 
Concho, Tex. | 
Erie, Peun. 
Pittsburg, Penn. 
Knoxville, Tenn. 
Vicksburg, Miss. 
Brackettville, Tex. 
Rochester, N.Y. 
Washington, D.C. 
Charlotte, N.C. 
Augusta, Ga. 
Mobile, Ala. 
This shows that in November, 1881, the cold 
waves were about two days in travelling from 
Fort Assinaboine to Washington. It would be 
an interesting comparison if a like investiga- 
tion were undertaken for waves of heat, also, 
during other months of the year. A similar 
method may be applied to the advance of 
waves of high and low pressure, with the great 
advantage that clouds would not interfere with 
the determination of the time of passage. 
This subject has attracted much attention 
from time to time, and recently it has been 
taken up by Mr. A. N. Pearson of India 
(Nature, Aug. 9, 1883). 
The chief signal-officer has kindly permitted 
this publication in advance of a more extended 
investigation. H. A. Hazen. 
TISSANDIER’S ELECTRIC BALLOON.1— I. 
In describing recently the new hydrogen-gas appa- 
ratus which we had constructed in our workrooms 
at Paris-Auteuil, we mentioned that the governable 
electric balloon, which has been in preparation since 
the electrical exposition, was ready for trial. This 
took place the 8th of last October. 
The arrangement of the controllable electric balloon 
consists of three distinct pieces of apparatus, —the 
air-balloon, properly so called; the gas apparatus to 
inflate it; and the electric motor to supply freedom 
of motion by means of a screw. 
The construction of an elongated aerial ship pre- 
sented serious difficulties. We were aided by two ex- 
periments, — that of Mr. Henri Giffard in 1852, and 
that of Mr. Dupuy de Léme in 1872. In the model 
which we tried at the time of the electrical exposi- 
tion, we arranged for the suspension of the little boat 
a low rod, running longitudina similar to that of 
the air steamship of Mr. Giffard. We afterward con- 
cluded that it would be better to place the screw be- 
hind a large parallelopiped-shaped boat, high enough 
to protect the propeller against the danger of a shock 
1 Translated from La Nature. 
and the deformations of the arrangement are escaped 
by means of a flexible shaft fixed at either side of the 
balloon. The balloon was constructed by my brother, 
in the rooms of Mr. H. Lachambre, to whom was 
intrusted the making of the new air-ship. A model 
15 cubic metres in capacity was first made; and, after 
studying the action of this in a captive state, the 
construction of the large balloon (fig. 1) was begun. 
Its shape was like that of Mr. Giffard’s and Mr. De 
Léme’s balloons: it was 28 metres long, and 9.2 me- 
tres in diameter through the middle. On its lower 
surface, there is a cone with an automatic valve: it 
is made of a thin cloth, rendered impermeable by a 
new varnish prepared by Mr. Arnoul of Saint-Ouen- 
VAnmone. The capacity of the balloon is 1,060 cu- 
bic metres. 
The netting over the balloon is formed of ribbons 
woven with longitudinal spindles, which keep them 
in their proper geometric positions. The ribbons 
thus easily adapt themselves to the inflated material, 
and do not form projections, as do the meshes of a 
net. The netting is connected on the sides of the 
balloon with two flexible shafts, which perfectly 
conform to its shape, passing along the centre of each 
side. The shafts are made of thin walnut laths fitted 
with bamboo: they are connected by silk belts. At 
the lower end of the netting are intersecting rods, at 
the ends of which are twenty suspension-ropes con- 
nected in groups of five to the four upper corners of 
the car. This latter is in the form of a cage made 
of bundles of bamboo rods, strengthened by cords and 
threads of copper covered with gutta-percha. ‘The 
lower part is made of walnut cross-pieces, which sup- 
port the willow basket. The suspension-ropes en- 
tirely cover the boat: they are woven into the basket, 
being previously sheathed in caoutchouc, which, in 
case of accident, protects them from the acid liquid 
contained in the boat to feed the batteries. ‘The sus- 
pension-ropes are connected horizontally by rigging 
about two metres above the boat. The guide and 
anchor ropes are attached to this rigging, which also 
serves to equally distribute the traction during the 
descent. The rudder, a broad surface of unvarnished 
silk supported by bamboo, is also arranged behind. 
The weights of the different parts are as follows: — 
